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Title:Spectroscopic studies of sonoluminescence
Author(s):Flint, Edward Baldwin
Doctoral Committee Chair(s):Kenneth S. Suslick
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, General
Chemistry, Physical
Abstract:Sonoluminescence is the light emitted from liquids during ultrasonic irradiation. This work is the first systematic investigation of sonoluminescence spectra from non-aqueous liquids. Sonoluminescence is caused by acoustic cavitation: the formation, growth, and collapse of bubbles in an acoustic field. The rapid collapse of these bubbles causes near-adiabatic heating of the gas and vapor contents of the bubbles.
Ultrasonic irradiation of alkanes, arenes, and silicone oil under Ar leads to emission from C$\sb2$, C$\sb2$H, and CH. When nitrogen is present emission from CN is observed, and when oxygen is present a continuum assigned to CO$\sb2$ emission is observed. Halocarbons under Ar give rise to emission assigned to Cl$\sb2$. A mechanism is proposed where vapor and gas molecules are fragmented by the high temperatures of the cavitation event. Subsequent reaction of high-energy free radical, atomic, and molecular fragments produces the emitting species.
A study of sonoluminescence spectra from alkali metal salts in primary alcohols was conducted as a test of the use of sonoluminescence as a probe of the cavitation event. The linewidths and peak positions of the resonance lines are independent of cavitational temperature. Radicals and atoms formed in the high temperature of the cavitation event were proposed to diffuse into a heated liquid shell surrounding the collapsed bubble, where they reduce and excite the alkali metal cations.
Synthetic spectra of the C$\sb2$ Swan band (d$\sp3\pi\sb{\rm g}$-a$\sp3\pi\sb{\rm u}$) were calculated to model the sonoluminescence spectra and determine the temperature of the cavitation event. Synthetic spectra were compared to sonoluminescence spectra from silicone oil under Ar. For the $\Delta\nu$ = +1 band, T = 4900 K; for the $\Delta\nu$ = 0 band, T = 5125 K; and by comparison of the two bands, T = 5200 K. The average of these determinations yields an effective temperature of the emitting C$\sb2$ in the cavitation event of T = 5050 $\pm$ 150 K.
Sonoluminescence spectra from solutions of metal carbonyls (M(CO)$\sb6$, M = Cr, Mo) are characterized by atomic emission from the metal. The compounds are decomposed and the atoms are excited by the high temperature of the cavitation event.
Issue Date:1990
Rights Information:Copyright 1990 Flint, Edward Baldwin
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9026179
OCLC Identifier:(UMI)AAI9026179

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